Industrial and utility concrete is often exposed to various acidic substances, and exposure to sulfuric acid is especially problematic for devices and structures in the mining industry, water treatment and chemical manufacturing plants, sewers, and manholes. To protect such structures from sulfuric acid vapors, mist, or liquid sulfuric acid, specialized film forming coatings can be applied. Alternatively, topical treatment of exposed structures with potassium silicate via dry gunning is also frequently employed for protection.
Unfortunately, coating failure using such conventional materials occurs rather frequently and subsequent damage to the underlying concrete progresses often rapid. The life expectancy of specialized acid resistant coatings such as epoxies, vinyl esters, and polyurethanes proofs to be substantially less than adequate and thus requires removal of the failed coating and re-application of a new coating. Moreover, even relatively small cracks in topical coatings will typically lead to substantial and rapid spreading damage. Surveillance of integrity of the coating is therefore often required, which adds to the significant cost of protection.
Likewise, re-coating of in service concrete surfaces is often problematic, and especially where the concrete was already subject to sulfuric acid attack. For example, unless salts, and especially sulfate salts, are removed from the surface and sub-surface areas of the concrete, new coatings will tend to fail and damage to the concrete will continue to develop. To avoid such damage, the surface of the concrete is in many cases treated by water blasting and/or treatment with selected complexing agents. However, water blasting and treatment with currently known complexing agents will often not provide sufficient salt removal, and re-coating is frequently required after only a very short time.
Therefore, even though numerous methods and compositions are known in the art to help protect concrete from sulfuric acid attack, all or almost all of them suffer from one or more disadvantages. Thus, there is still a need for improved compositions and methods of protecting cured concrete and cementitious materials.